Intervertebral spacer device utilizing a spirally slotted belleville washer having radially spaced concentric grooves

Abstract

An intervertebral spacer device having a pair of opposing plates for seating against opposing vertebral bone surfaces, separated by at least one spring mechanism. The preferred spring mechanism is at least one spirally slotted belleville washer having radially spaced concentric grooves. In a preferred embodiment there is a single such belleville washer which is modified to mount onto a ball-shaped head. The lower plate of this embodiment includes a post extending upwardly from the inner surface of the plate, the post including a ball-shaped head. The modified belleville washer can be rotatably mounted to the head such that the wider portion of the washer seats against the upper plate.

Description

CROSS-REFERENCE TO RELATED APPLICATION[0001]This application is a continuation application of U.S. patent application Ser. No. 09 / 975,471 (filed Oct. 11, 2001) entitled “Intervertebral Spacer Device Utilizing A Spirally Slotted Belleville Washer Having Radially Spaced Concentric Grooves”, now U.S. Pat. No. 6,863,688 (“the '688 patent”), which is a continuation-in-part of U.S. patent application Ser. No. 09 / 970,479 (filed Oct. 1, 2001) entitled “Intervertebral Spacer Device Utilizing A Spirally Slotted Belleville Washer Having Radially Extending Grooves”, now U.S. Pat. No. 6,669,730 (“the '730 patent), which is a continuation-in-part of Ser. No. 09 / 968,046 (filed Oct. 1, 2001) entitled “Intervertebral Spacer Device Utilizing A Belleville Washer Having Radially Extending Grooves”, now abandoned. of the above mentioned applications are hereby incorporated byFIELD OF THE INVENTION[0002]This invention relates generally to a spinal implant assembly for implantation into the intervertebral...

AI Technical Summary

Benefits of technology

The present invention is a flexible intervertebral spacer device that can be positioned between the facing surfaces of adjacent vertebral bodies. The device consists of two base plates that are connected by a spring mechanism. The spring mechanism provides a restoring force when a compressive load is applied to the plates, and allows rotation of the plates relative to each other. The plates can be designed to not rotate relative to the bone surfaces they are in contact with. The device can be made from a variety of materials that are compatible with the human body and can withstand cyclical loading. The use of a belleville washer as a restoring force providing subassembly is preferred.

Problems solved by technology

It is, however, important to note that the fusion of the adjacent bones is an incomplete solution to the underlying pathology as it does not cure the ailment, but rather simply masks the pathology under a stabilizing bridge of bone.

This bone fusion limits the overall flexibility of the spinal column and artificially constrains the normal motion of the patient.

This constraint can cause collateral injury to the patient's spine as additional stresses of motion, normally borne by the now-fused joint, are transferred onto the nearby facet joints and intervertebral discs.

Images